Method of producing nitrocellulose



Patented Oct. 29, 1946 METHOD OF PRODUCING NITRO- CELLULOSE Henry VonKohorn, New York, N. Y.

No Drawing. Application May 22, 1941, Serial No. 394,619

Claims. (01. 260--222) My invention relates to an improvednitro-cellulose having a high and stable nitrogen content, and. to amethod of producing the same.

It also relates to the manufacture of nitrocellulose or cellulosenitrate with a more stable nitrogen content than known up to now, fromcellulose-containing materials which are comparatively poor incellulose. I can produce 'by the method hereinafter described asatisfactory nitro-cellulose from raw materials heretofore consideredunsuitable for the manufacture of nitrocellulose.

Up to the present time, nitro-cellulose has been mainly produced frompurified cotton or other cellulosic material which was purified to suchan extent as to contain almost only pure alpha-cellulose. There exist,of course, a large number of cellulose-containing plants of analpha-cellulose content of less than 80% and such materials have beenconsidered unsuitable for the manufacture of nitro-cellulose.

Nitro-cellulose was produced by dipping purified cotton or otherpurified cellulosic matters into a bath containing, for example, 60%-sulphuric acid, 23% nitric acid and 17% water. Another suggestednitrating solution contained of sulphuric acid and /5 nitric acid, thebalance being water. The cellulose is left in this bath for a sufficientlength of time, for instance one hour,

at a temperature which was not allowed to rise freely but which Was keptconstant.

The use of purified cotton linters or even pure alpha-cellulose preparedfrom other cellulose-containing materials,. such as wood, straw, reeds,or other plants, is of course a costly one due to the purification. Alsothe nitration of such fibrous matters by the method described above doesnot result in a very stable nitrogen content of the nitro-cellulose, andmany attempts have been made to improve the stability of the saidnitrogen content.

I have discovered a method which enables me to use as raw material notonly materials containing 100% alpha-cellulose, but also manycellulose-containing materials comparatively poor in alpha-cellulosecontent. In addition to this, my method results in a nitro-cellulosehaving a more stable nitrogen content which, if required, may also behigher than produced heretobefore.

According to my invention, nitro-cellulose having a high and stablenitrogen content is man ufactured by bringing cellulose orcellulose-containing materials into solution by any of the known methods(viscose, cuprammonium, acetate), and then regenerating said celluloseand at the same time nitrating it; by precipitating the solutioncontaining dissolved cellulose in a bath which not only has aprecipitating, but at the same time, a nitrating effect on theregenerated cellulose. 7 a

I shall now describe in detail how I carry out my improved process. Whenspeaking of cellulose herein, I refer to alpha-cellulose.

Example 1 Wood pulp with a cellulose content of 83% is dissolvedaccording to the viscose method into viscose containing 16%alpha-cellulose. The said viscose is squirted through a spinneret into abath containing by weight of sulphuric acid :and /5 of nitric acid, thebalance of the bath being water. The threads formed are wound up on abobbin, which bobbin runs in the same bath. When the bobbin iscompletely Wound, the threads are unwound and boiled in water in orderto remove the acid.

The threads are then dried and cut into pieces.

Example 2 Emample 3 The cellulose is dissolved into viscose and the saidviscose is stored until it is so ripe as to be close to the coagulationpoint. The viscose is then forced through spinnerets into a bathcontaining 55% sulphuric acid, 25% nitric acid and 20% water. Thefibrous mass obtained is then removed from this first bath and isimmediately placed, without :intermediate treatment, into a second bathcontaining sulphuric acid, /5 nitric acid and the balance consisting ofwater.

After remaining in the second bath for 30 minutes, the fibers areremoved, desulphurized by treatment with sodium sulphide solution,washed and dried.

. Example 4 Wood pulp with a cellulose content of is brought intosolution according to the viscose method. The viscose is delivered intoa bath containing /3 of sulphuric acid, A; of nitric acid, the balancebeing water. The regenerated cellulose is kept in this bath for 30minutes at a temperature of 25 C.

Example 5 Cellulose is regenerated and nitrated as in Example 4 with thedifierence that the time during which the cellulose is kept in the bathis 90 minutes.

By following any one of the above-described examples, clifierent typesof Intro-cellulose are As another feature of my invention (as deproducedwhich may have varying contents of scribed in the examples), Ihavediscovered that nitrogen, but which are extremely stable; It ismy'process can be carried out very economically obvious that by applyinga nitrating agent to the by producing a cellulose solution with a highcelcellulose while still in the status nascendi, the 5 lulose contentwhich ordinarily would. not be mtratmg efiect is much stronger and morethorconsidered suitable for the manufacture of rayon.

ggg ar gai ufo appljeld to oroinary solid cellu- [In View Of Z126 T6205[11% I125 flfl/ V/% v llW/

